This invention relates to an apparatus for forming plastic material gaskets in stoppers comprising a cup, such as screw-on and crown caps.
As is known, in the manufacture of crown caps, among the various techniques used heretofore to form the cap gasket, there are some which provide for the introduction, through different arrangements into the cap metal cup, of a preset amount of an extruded plastic material, generally in a softened state, which is subsequently cold molded. The machines used to implement such prior techniques have all the problem of being unable to adequately introduce the metered extruded amount into the cap, where the latter happens to have a fairly large height dimension. In fact, current apparatus employed for the formation of said gasket substantially comprise a first carousel, which carries peripherally a plurality of metal cups, and a second carousel, or alternatively, various rotary knife devices or the like, which are arranged to operate tangentially to the path of movement of the caps to be provided with that metered amount of plastic material therein.
In all cases, the useful section for effecting said introduction of the metered amount has obviously a limited length, thereby the apparatus is required to operate at a high rate, which increases its complexity and the likelihood of faulty gaskets being formed.
It is also apparent that this imposes limitations on the carousel rotational speed or introducing device rate, thus limiting the apparatus output rate.